U.S. patent application number 13/255335 was filed with the patent office on 2012-03-08 for feeding apparatus and method.
This patent application is currently assigned to SACMI VERONA S.P.A.. Invention is credited to Damiano Fabbri, Maurizio Pedercini.
Application Number | 20120055297 13/255335 |
Document ID | / |
Family ID | 41226871 |
Filed Date | 2012-03-08 |
United States Patent
Application |
20120055297 |
Kind Code |
A1 |
Pedercini; Maurizio ; et
al. |
March 8, 2012 |
FEEDING APPARATUS AND METHOD
Abstract
An apparatus (1) and a method for feeding a continuous tape (3)
for forming labels (2) is disclosed, according to which a pair of
rollers (5) advances the tape at an advancing speed that is
calculated on the basis of the rotation speed of one cutting roller
(6) that cuts the tape into labels, (2) at a signal that is
indicative of the cut that occurred and at a positioning error of
an actual image present on the tape with respect to a reference
image. The real image is detected by a linear camera (9) or by a
matrix camera.
Inventors: |
Pedercini; Maurizio;
(Marmirolo (MN), IT) ; Fabbri; Damiano; (San
Giorgio di Mantova (MN), IT) |
Assignee: |
SACMI VERONA S.P.A.
Imola
BO
|
Family ID: |
41226871 |
Appl. No.: |
13/255335 |
Filed: |
March 5, 2010 |
PCT Filed: |
March 5, 2010 |
PCT NO: |
PCT/IB2010/050953 |
371 Date: |
November 14, 2011 |
Current U.S.
Class: |
83/13 ;
83/74 |
Current CPC
Class: |
B65H 23/1882 20130101;
H01L 27/14601 20130101; Y10T 83/04 20150401; B26D 1/626 20130101;
B26D 5/34 20130101; Y10T 83/4458 20150401; B65C 9/44 20130101; B26D
5/32 20130101; B65C 9/1803 20130101; B65H 2301/5151 20130101; B65H
2553/42 20130101; Y10T 83/148 20150401; B26D 1/405 20130101; B26D
5/007 20130101 |
Class at
Publication: |
83/13 ;
83/74 |
International
Class: |
B26D 5/20 20060101
B26D005/20; B26D 5/00 20060101 B26D005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2009 |
IT |
MO2009A000050 |
Claims
1-10. (canceled)
11. An apparatus comprising: a feeding device configured for
feeding a continuous tape along a path in an advancing direction; a
cutting device configured for cutting a tape that advances along
said path with a cutting line transverse to said advancing
direction; a first sensor configured for emitting a plurality of
first signals indicative of an image located on a tape that
advances along said path; and a controller configured for
performing the following operations: driving said feeding device to
feed a tape along said path; receiving said plurality of first
signals and comparing at least a part of said first signals with
stored reference signals; and controlling said driving on the basis
of said comparison; said first sensor comprising a plurality of
sensitive elements spaced apart from one another in a direction
that is transverse to said advancing direction, each of said
sensitive elements being configured for emitting a signal that is
indicative of a respective portion of said image, wherein said
apparatus further comprises a third sensor configured for emitting
at least a third signal indicative of an operating parameter of
said cutting device, said operating parameter being a function of
time or being variable during operation of said cutting device,
said controller being configured for receiving said at least a
third signal and for controlling said driving, not only on the
basis of said comparison but also on the basis of said at least a
third signal.
12. An apparatus according to claim 11, wherein said controller is
configured for periodically receiving the signals emitted by said
sensitive elements for acquiring a series of single transverse
image portions and for comparing said series of single transverse
image portions with a series of stored reference single transverse
image portions.
13. An apparatus according to claim 11 or 12, wherein said first
sensor comprises a linear camera arranged on said path transversely
to said advancing direction.
14. An apparatus according to claim 11 or 12, wherein said first
sensor comprises a matrix camera operationally arranged on said
path.
15. An apparatus according to claim 11 or 12, and further
comprising an aligning device for adjusting the position of the
tape in a direction that is transverse to said advancing direction,
said controller being configured for controlling said aligning
device on the basis of said first signals.
16. An apparatus according to claim 11 or 12, and further
comprising a second sensor configured for emitting at least a
second signal indicative of the moment in which said cutting device
assumes a given operating configuration, said controller being
configured for selecting a group of said first signals as a
function of said moment indicated by said at least a second signal
and for comparing said group of said first signals with a stored
group of reference signals.
17. An apparatus according to claim 11 or 12, wherein said
comparing operation comprises processing said plurality of first
signals to determine an actual image, processing said stored
reference signals to determine a reference image, and determining a
position error in said advancing direction between the position of
said actual image and the position of said reference image; said
operation of controlling said driving comprising controlling the
advancing speed of said tape on the basis of an operating speed of
said cutting device and of said position error.
18. An apparatus according to claim 16, wherein said second and
said third sensor are integrated into a single sensor.
19. A method comprising the steps of: feeding a continuous tape
along a path in an advancing direction, said tape having an image;
cutting said tape that advances along said path with a cutting line
transverse to said advancing direction; emitting a plurality of
first signals indicative of said image and comparing at least a
part of said first signals with stored reference signals;
controlling said feeding of the tape on the basis of said
comparison; wherein each of said first signals comprises signals
indicative of portions of said image arranged spaced apart from one
another in a direction that is transverse to said advancing
direction.
20. A method according to claim 19, wherein said comparing
operation comprises acquiring a series of single transverse image
portions and putting said series of single transverse image
portions in a relation to a series of stored reference single
transverse image portions.
Description
BACKGROUND TO THE INVENTION
[0001] The invention relates to an apparatus and a method for
supplying a continuous tape.
[0002] Specifically, but not exclusively, the invention can be used
in the context of an apparatus for forming labels from a continuous
tape (generally unwound from a reel) that has, distributed along
the length thereof, a series of images that are preprinted and
spaced apart from one another by a preset space (pitch) and will
form the images on the labels.
[0003] As known, this pitch can be variable from one reel to
another according to requirements, or even, can vary in the context
of the same reel, sometimes also because of printing or unwinding
errors.
[0004] A problem with known printing apparatuses is thus that of
forming some labels from a continuous tape bearing the images, in
which each image is centred on the label, whatever the pitch of the
images distributed along the tape, even in the event of printing or
unwinding errors that may have modified the nominal pitch of the
images and/or may have distorted the images with respect to the
desired distribution.
[0005] In order to overcome this problem, from WO 2006/061775 a
continuous tape feeding apparatus is known in which a feeding
device advances a tape along a path, a sensor detects an image on
the advancing tape, a cutting device cuts the tape transversely
into labels and a controller compares the detected image with a
reference image and then adjusts the advancing speed of the tape on
the basis of the aforesaid comparison in order to cut the tape in
the correct position to form labels with a perfectly centred
image.
[0006] The sensor used in the apparatus disclosed in WO 2006/061775
for detecting the image is a pixel optical sensor, or a band
optical sensor that emits a signal indicative of the average value
that a given optical feature assumes (for example luminous
intensity) in a preset portion of the surface of the tape. Various
aspects of the apparatus shown by WO 2006/061775 are
improvable.
[0007] In the first place it would be advantageous to eliminate or
minimise the risk of errors in the forming of the label that are
due to a programmed or not programmed or also undesired variation
in the operating parameters of the cutting device in the course of
advancing of the continuous tape.
[0008] In the second place it would be desirable to improve the
precision and reliability of the known apparatus, for example by
reducing the negative effects due to possible transverse movements
of the tape in relation to the advancing direction thereof, effects
which may compromise the correct operation of the apparatus in WO
2006/061775. It has been observed that in WO 2006/061775 the use of
the band sensor, that on the one hand can help reduce to a certain
extent the imprecision due to undesired transverse movements of the
tape and on the other hand is imprecise through the nature
thereof.
[0009] It would be further desirable to improve efficacy in
monitoring the print quality of the image in the tape and/or in
recognising malfunctions of the feeding apparatus (for example
errors in mounting the reel and/or the tape) and/or in identifying
the size of the tape and of the corresponding label.
SUMMARY OF THE INVENTION
[0010] An object of the invention is to improve one or more of the
aspects mentioned above of the apparatuses for feeding tapes for
labels, in particular the apparatus shown by WO 2006/061775.
[0011] Another object is to provide a method for feeding tapes for
labels on the basis of which being able to monitor effectively a
feeding apparatus.
[0012] Still another object is to make an apparatus and/or a method
for feeding a tape for labels that is able to adapt rapidly and
precisely to any possible change (expected or unexpected) in the
operating situation of the labelling apparatus that applies the
labels to objects.
[0013] An advantage of the invention is to eliminate or minimise
the risk of errors in the formation of the label that are due to
undesired transverse movements of the tape.
[0014] Another advantage consists of providing an apparatus and/or
a method owing to which it is possible to perform, with great
precision and reliability, monitoring, and possibly feedback
control by using a tape aligning device of known type for aligning
the position of the tape in a transverse direction (alignment).
[0015] A further advantage is to make an apparatus and/or a method
available that enables labelling quality to be controlled
effectively, in particular in terms of detecting the print quality
of the images on the tape, identifying the size of the tape coupled
with the feeding device, checking that the label being processed
corresponds to the label it is desired to produce (desired label
corresponding to a stored reference image), recognising the correct
coupling of the tape with the feeding device, etc, etc.
[0016] One or more of such purposes and advantages and still others
are achieved by the apparatus and method according to one or more
of the claims set out below.
SHORT DESCRIPTION OF THE DRAWINGS
[0017] The invention can be better understood and implemented with
reference to the attached drawings that illustrate some embodiments
thereof by way of non-limiting examples.
[0018] FIG. 1 shows a diagram of an example of the apparatus made
according to the present invention.
[0019] FIG. 2 is a diagram illustrating a possible manner of
detecting the images on the moving continuous tape according to the
present invention.
[0020] FIG. 3 is a diagram illustrating a possible manner of
comparing a detected image with a stored reference image.
[0021] FIG. 4 is a possible control diagram for controlling the
advance of the continuous tape displaying the images with which to
form the labels.
DETAILED DESCRIPTION
[0022] With reference to the aforesaid figures, with 1 an apparatus
has been overall indicated that provides labels to a labelling
apparatus (known and not illustrated), with 2 a label provided by
the apparatus 1 to an outlet end of the apparatus is shown, the
outlet end being connected to the labelling apparatus, with 3 a
continuous tape is indicated that displays the images that will
form the labels (in the example the images of the labels have been
represented for the sake of simplicity by way of example with a
series of "A"), with 4 a reel is indicated from which the tape 3 is
unwound, with 5 a feeding device is indicated that supplies the
continuous tape 3 along a path in an advancing direction, with 6 a
cutting device is indicated that cuts the tape 3 that advances
along the path with a cutting line that is transverse to the
advancing direction. The apparatus may further comprise an aligning
device that is known and not illustrated that is configured for
regulating the transverse position of the tape, i.e. the alignment
with respect to an advancing axis or longitudinal axis of the
tape.
[0023] The feeding device 5 may comprise any type of advancing
system (optionally continuously, as in the specific example, or
intermittently) of a continuous tape. In the specific case the
feeding device 5 optionally comprises at least one pair of
counter-rotating conveying rollers through which the tape passes
with a dragging effect. The feeding device 5 is provided with
driving means optionally comprising at least one motor 7. In the
specific case at least one of the two conveying rollers is rotated
by the motor 7, which is controlled by a control and command system
8 (comprising for example one or more known controllers/computers
of known type, PLC, PC, Inverter, etc) to which appropriate command
instructions are sent, as will be explained better further below in
this description.
[0024] The cutting device 6 may comprise any known type of system
that is suitable for transverse cutting (for example perpendicular
to the advancing direction of the tape and/or to the longitudinal
extent thereof) of a continuous advancing tape (continuously or
intermittently) to form a series of discrete elements (labels 2) of
a preset length L. The cutting device 6 optionally comprises at
least one cutting roller provided with at least one blade 10 (with
a cutting line transverse to the tape and parallel to the rotation
axis of the roller) that cyclically, with an operating period that
depends on the rotation speed of the cutting roller, transversely
cuts a piece of tape. The blade 10 operates in general in
cooperation with a contrasting element (for example a fixed
counter-blade or counter-blade carried by a further
counter-rotating roller in a synchronised manner). The cutting
device 6 could comprise two or more blades, which are, for example,
arranged on the rotating supporting roller and are angularly
(equi)distant from one another. The cutting device could comprise a
device of non-mechanical type, such as, for example, a
cutting/engraving device of laser type, for example like the one
disclosed in patent WO 2007/110738. The cutting device 6 is
provided with driving means optionally comprising at least a motor
11, as in the illustrated example, or a system (for example
mechanical) for connecting with other moving mechanical members of
the labelling apparatus (as for example the rotating conveying
carousel), in which case it is possible to set up a position or
movement sensor connected to the system (for example an absolute or
relative encoder or a resolver), which sensor can be used
optionally to control the cutting operation. As in the specific
case disclosed here, at least one cutting roller can be rotated by
the motor 11, which is controlled by a control and command system
(which is known and not illustrated) which could be distinct from
(or be integrated into) the controlling system 8 for controlling
the advancing of the tape 3 and which controls the cutting device 6
on the basis of setting values that are optionally preselected in
function of the operating requirements and/or mode of a labelling
apparatus (which is known and not illustrated) arranged below the
cutting device 6.
[0025] The apparatus 1 comprises a system of various sensors
connected to the controlling system 8 for controlling the
apparatus. In particular, the apparatus comprises a first sensor 9
for detecting an image on the tape 3, as will be explained more
fully further on in the description. The apparatus 1 comprises a
second sensor, which is known and not illustrated, that may
comprise a single sensor or a group of sensors or a set of sensor
means. The second sensor is configured for emitting at least a
second signal 13 that is indicative of the moment in which the
cutting device 6 assumes a certain operating configuration. The
second sensor may optionally comprise an encoder (which is known
and not illustrated) that is operationally associated with the
cutting roller and configured for emitting a determined signal (for
example a zero position signal) at a preset position of the roller
(as for example the position that corresponds to the moment of
execution of the cut of the tape). The control and command system 8
is configured for recognising the aforesaid determined signal
(second signal 13) and for consequently defining the moment in
which a given operation occurs and/or in which the cutting device 6
assume a certain operating configuration.
[0026] The apparatus comprises a third sensor (a single sensor or a
group of sensors or a set of sensor means) configured for emitting
at least a third signal 12 indicative of an operating parameter of
the cutting device. The third signal 12 indicates an operating
parameter of the cutting device 6 that is optionally a function
parameter of time or parameter that is variable during operation of
the cutting device. This parameter may be the operating speed of
the cutting device 6 (for example the rotation speed of the cutting
roller that is detectable by a speed sensor of the type which is
known and not illustrated) or another function parameter of the
time or the position of a movable element of the cutting device 6
or another parameter that is variable during operation of the
cutting device.
[0027] The second and the third sensor can be integrated into a
single sensor (or group of sensors or set of sensor means) that can
perform both the aforesaid functions, such as, for example, an
absolute encoder.
[0028] The control and command system 8 of the advance of the tape
3 is connected to the cutting device 6 so as to be able to receive
the aforesaid third signal 12 indicative of an operating parameter
of the cutting device 6 (in particular the speed of an operating
element of the cutting device such as for example, as already said,
the rotation speed of the cutting roller). The control and command
system 8 in particular could be connected to the cutting tool
and/or to the driving means of the cutting device 6 and/or to the
control and command system of the cutting device 6. The signal 12
could comprise, for example, a signal (for example the `speed`
signal) of an encoder or a resolver, for example also in the
specific case in which the cutting device 6 is not equipped with
its own independent motor drive (comprising for example the motor
11), but is driven by a (mechanical) connecting system with other
moving members (in which case the aforesaid encoder or resolver can
be connected to this connecting system).
[0029] The control and command system 8 of the advance of the tape
3 is connected to the cutting device 6 such as to be able to
receive the aforesaid second signal 13 that is indicative of the
fact that the cutting device 6 has assumed a particular operating
configuration (such as, for example the operating configuration
that coincides with the moment of execution of the cut of the
tape). If the cutting device 6 is provided with two (or more
blades) 10, at each revolution of the cutting roller two (or more)
second signals 13 will be generated. The second signal 13 could
comprise a signal (for example the `zero` trace) emitted by the
aforesaid encoder or resolver that generates the signal 12 (`speed`
signal), in particular in the case cited above in which the cutting
device 6 is driven via a connecting system connected (mechanically)
with other moving members.
[0030] As said, it is possible to use an absolute encoder (rather
than a relative or incremental encoder), in which case the provided
signal can be used both to detect a determined operating parameter
of the cutting device and for determining when the device has
assumed a particular operating configuration; in substance it is
possible to use a single type of signal to obtain the indications
disclosed above, which are provided by the two types of signal 12
and 13. The apparatus 1 that provides labels 2 comprises, as said,
the first sensor 9, which is configured for emitting and sending to
the control and command system 8 a plurality of first signals 14
indicative of an image located on the tape 3 advancing along the
supply path. The first sensor 9 comprises a plurality of
photosensitive elements arranged spaced apart from one another in a
direction that is transverse to the advancing direction of the
tape. In particular, the photosensitive elements can be arranged
aligned in a direction that is perpendicular to the advancing
direction of the tape. The first sensor 9 may in particular
comprise an image acquisition device in which the photosensitive
elements are relatively numerous and are arranged for forming a
line (for example a linear camera) arranged transversely
(perpendicular) to the direction of longitudinal extent or
advancing of the tape. The first sensor 9 may comprise a linear
camera or other device configured for acquiring a line-by-line
image.
[0031] The first sensor 9 may comprise, for example, a camera of
matrix type (photosensitive elements arranged as a matrix or a
grid) that acquires the image by square, in which the acquisition
zone relates to at least all or almost all the width of the tape.
In particular, the first sensor 9 could be configured for operating
on an image acquisition zone that extends laterally beyond the
width of the tape, i.e. beyond at least a side edge of the tape
(beyond one of the two side edges of the tape or, as in the
illustrated example in FIG. 1, beyond both the side edges of the
tape).
[0032] The choice of the number and dimensions of the
photosensitive elements depends, as is known in an image
acquisition device, on a compromise between resolution and
sensitivity that will in turn depend on the specific use parameters
(tape width, type of image, etc). Also the choice of the type of
sensitivity of the photosensitive element (colour, black and white,
etc) and the sampling speed and other features that may distinguish
the image acquisition device, will depend on the operating
conditions of the feeding apparatus and is not discussed in greater
detail.
[0033] The first sensor 9 comprises a plurality of photosensitive
elements of pixel type, optionally arranged aligned along a line
that is transverse to the advancing direction of the tape so as to
analyse an image line arranged transversely on the tape.
[0034] The first sensor 9 is arranged before the cutting device 6
and can be arranged before the feeding device 5 or, as in the
illustrated example, after this device.
[0035] It is possible to arrange, in an example that is not
illustrated, one or more further first sensors (for example cameras
of linear type) each arranged also transversely to the tape and
spaced apart in the length of the tape with respect to the first
sensor 9, to have a signal redundancy. In FIG. 2 there is
illustrated schematically the mode for detecting the image made by
the first sensor 9, that sends a series of single image lines I1,
I2, . . . , IN, (with a preset acquisition frequency that could be
linked to the operating speed of the cutting device 6) to the
control and command system 8 that composes the image,
reconstructing it, for example by plotting a composition
(Itot=I1+I2+ . . . Ik+ . . . +IN as illustrated in FIG. 2) of the
single detected image lines. Each image line will comprise a set of
signals (signals vector) provided by the various sensitive elements
that make up the sensor 9.
[0036] The control and command system 8 is configured for
controlling the apparatus 1, making the apparatus 1 perform the
operations disclosed below, the configuration of the system 8 being
achievable, for example, via an instructions programme (software)
associated with the system 8. The control and command system 8
could be implemented in any of the known implementation modes of a
general controller, such as, for example, by transmitting
information (instructions) from a remote source, or by entering
information (instructions) contained in removable or fixed
supporting means, etc.
[0037] The control and command system 8 can control the apparatus
with the following operating cycle: the controlling system 8
receives the third signal 12 and on the basis of the third signal
12 determines the acquisition frequency of the first signal 14 and
the advancing speed of the tape 3; then at the arrival of the
second signal 13 it closes the image composition.
[0038] In particular the system 8 is configured for driving the
feeding device 5 for feeding the continuous tape 3 along the preset
path; the system 8 is further configured for receiving the first
signals 14 to identify the image on the tape 3; the system 8 is
further configured for selecting a group of first signals 14 in
function of the moment indicated by the second signal 13. In
substance, the control and command system 8 can group the image
signals (first signals 14) to form a group that includes the
signals that are carried between two moments identified by two
(consecutive) second signals 13. The control and command system 8
is configured for comparing the group of first signals 14 thus
defined (which represents the actual image Ia that passed in front
of the first sensor between the emission of two consecutive second
signals 13) with a stored group of reference signals Iref (see FIG.
3) and then controls the drive of the feeding device 5 (for example
by adjusting the speed of at least one of the feeding rollers) on
the basis of the aforesaid comparison and on the basis of the third
signal 12.
[0039] In particular the comparing operations comprise the
calculation of a length "e" (said phase error) determined by the
difference (longitudinally) between the position of the reference
image Iref and the position of the actual image Ia (as shown in
FIG. 3), this difference "e" being in substance a position
displacement considered with reference to the advancing direction
of the tape. This length "e" thus represents a positioning error in
the advancing direction that can be corrected by appropriate
modification of the feed of tape 3 (for example by varying the
rotation speed of the feeding roller). In the specific case the
feeding device 5 is commanded to advance the tape by an amount
equal to Lr=Lt+.DELTA.L (where Lr is the real actually measured
length of the label, Lt is the theoretical length of the label and
.DELTA.L is a correction length depending on the phase error "e"
and is calculated on the basis of this error) in the period of time
T that elapses between two (chronologically consecutive) cuts of
the tape. The dependency between the correction length .DELTA.L and
the phase error "e" is a function of an algorithm that links
.DELTA.L and "e" and which may comprise, for example, a regulator
of any type, in particular a PI regulator (as in the example of
patent WO 2006/061775) or a PID regulator or a mathematical model
that places .DELTA.L and "e" in a relation.
[0040] The aforesaid period T, which can, for example, be the same
as the time that the cutting roller takes to perform a complete
revolution (if the cutting device has only one blade 10), is not
necessarily constant but may depend, for example, on one or more
operating parameters of the labelling apparatus (for example on the
production speed of the apparatus).
[0041] It should be noted that the reference image Iref, which is
used in the comparison operation for determining the positioning
error or phase error "e" as seen previously, can be memorised
according to an initial acquisition procedure (learning) that may
comprise, for example, the initial learning procedure disclosed in
WO 2006/061775 which is incorporated for reference. This initial
acquisition procedure will be run, in general, only once for each
image and/or label size used on the apparatus, in general at the
first use of the size. This learning procedure may comprise, in
brief, an operation of unwinding the tape 3 from the reel (also
manually) by a desired amount L (nominal length of label for a
certain size) so as to enable the first sensor 9 to send the first
signals 14 that will enable the controlling system 8 to compose the
Iref reference image.
[0042] It is observed, for completeness, that to obtain correct
centering of the label, whatever the Iref reference image acquired
during the learning phase, it is possible to consider a further
offset value, as has been disclosed in pages 17 and 18 of WO
2006/061775, which is incorporated here for reference.
[0043] A practical embodiment of how the control method of the
apparatus 1 according to the invention could be implemented is
disclosed below.
[0044] The cutting device 6 is set (in particular the speed of the
cutting roller is set) taking account of the needs of the labelling
apparatus (not illustrated) arranged downstream. For this purpose
it is possible, for example (as already said), to arrange a
mechanical connection between an operating element (for example a
conveying carousel of the objects to be labelled) of the labelling
apparatus, or, in another example, by setting the driving means
(for example the motor 11) of the cutting device 6 so that the
latter follows the aforesaid operating element (to a conveying
carousel), for example by controlling the speed of the cutting
device 6 with a setting value that is proportional to a (setting
and/or measured) value of the aforesaid operating element (for
example the rotation speed of the conveying carousel).
[0045] If there is only one blade 10 on the cutting roller, at each
complete revolution (360.degree. revolution) of the cutting roller,
the blade 10 will cut a label 2 from the (continuously) advancing
tape 3.
[0046] The feeding device 5 is driven by the motor 7, which is
controlled so that at each revolution of the cutting device 6, the
feeding device 5 has wound a length Lr of tape, where Lr will be
the actual length of print impressed on the tape that will define
the length of the label.
[0047] Driving the feeding roller will produce the unwinding of a
portion of length Lr of the tape 3 from the reel 4 in the time T
that is equal to the period of a complete revolution of the cutting
roller. The speed of the feeding roller will thus be determined by
taking into account the speed of the cutting roller.
[0048] Thus at each complete rotation (one revolution) of the
cutting roller, the feeding roller should unwind a certain length
of tape 3 from the reel 4 and thus pass a portion of tape of the
same length in front of the first sensor 9 (linear camera or matrix
camera).
[0049] At each fraction of a revolution of the cutting roller, the
first sensor 9 will detect a fraction (in particular at least one
line if the first sensor 9 comprises a linear or matrix camera) of
Ik image (see FIGS. 1 and 2).
[0050] The acquisition frequency of the first signal 14 will be
optionally proportional to the operating speed of the cutting
device 6 that is determined by the signal 12. During rotation of
the cutting roller the first sensor 9 (linear or matrix camera)
will acquire a multiplicity of image lines I1, I2, . . . , In,
forming an Itot image consisting of the composition of the single
image lines, i.e. Itot=I1+I2+ . . . +In. The image Itot will in
effect consist of the control and command system that will
comprise, for example, the same (electronic) processing unit with
which the linear or matrix camera can be provided.
[0051] Further, at each complete revolution of the cutting roller,
the cutting device 6 will provide a second signal 13 (cut performed
signal) to the controlling system 8 that will associate this signal
13 with the sum of the signals of the image Itot. The controlling
system 8 will thus store the image Itot reconstructed up to the
moment of receipt of the signal 13 (until the cutting performed
moment) and the image that is thus stored will be considered the
real final image Ia that will be the object of the subsequent
comparison. In substance, at each cut of the tape (i.e. in the
specific case in which the cutting roller has a single blade 10, at
each complete rotation of the cutting roller) the controlling
system 8 defines and stores the actual image Ia that has actually
passed in front of the first sensor 9 (linear or matrix
camera).
[0052] This actual image Ia will then be compared by the
controlling system 8 with the previously acquired Iref reference
image and will thus determine the positioning error "e" that is
equal to the distance (in the advancing direction of the tape 3)
between Ia and Iref. The system 8 will then calculate the
correction distance .DELTA.L (.DELTA.L being calculated in function
of "e", for example by a PI or PID regulator), i.e. the length of
tape that the feeding device 5 has to unwind, more or less, with
respect to the (theoretical) nominal preset length Lt in the period
of time T that passes between two consecutive cuts (cutting
period).
[0053] In brief, the control and command system 8 is programmed so
as to unwind from the reel 4 a length of tape 3 that is the same as
Lt+.DELTA.L in the period of time T (i.e. the cutting period, which
can be variable and is determined each time, in real time, in
function of the speed of the cutting roller send to the system 8
with the third signal 12).
[0054] The effect of the correction of the speed of the feeding
roller will be to return the actual image Ia in phase with the Iref
reference image so as to centre the image on the label 2.
[0055] The feeding apparatus can comprise, as said, an aligning
device for tapes, of a type which is known and not illustrated,
which regulates the position of the tape in transverse direction
(in particular perpendicular) to the length of the tape, i.e. to
align the tape that advances to position the tap in axis with a
desired advancing line. The signals supplied by the first (optical)
sensor 9, comprising for example a linear camera, can be used to
perform feedback control of the alignment, in which case the
control unit (system 8) acquires one or more of the single image
lines Ik, to process the image line Ik acquired for determining the
position of the image in a transverse direction (alignment),
comparing said position of the image with a reference that
indicates the correct alignment of the tape, and commanding the
aligning device so as to correct a possible alignment error of the
advancing tape.
* * * * *